https://llvm.org/bugs/show_bug.cgi?id=30784
Bug ID: 30784
Summary: Reassociate removes call but preserves CG, asserts
Product: tools
Version: trunk
Hardware: PC
OS: Linux
Status: NEW
Severity: normal
Priority: P
Component: opt
Assignee: unassignedb...@nondot.org
Reporter: jesper.antons...@ericsson.com
CC: llvm-bugs@lists.llvm.org
Classification: Unclassified
Created attachment 17486
--> https://llvm.org/bugs/attachment.cgi?id=17486&action=edit
Reduced ll file exposing the bug
The reassociate pass may remove a call and then falsely claim to preserve the
CG. This later leads to this assert at dead function removal:
opt: ../include/llvm/Analysis/CallGraph.h:184:
llvm::CallGraphNode::~CallGraphNode(): Assertion `NumReferences == 0 && "Node
deleted while references remain"' failed.
One simple fix is to set the variable MadeChange to true in
RecursivelyEraseDeadInsts() if operating on a CallInst. (However, the
preservation code acting on MadeChange has a comment indicating that even when
set to true it should preserve the CG, but currently it does not.)
The attached ll-file can be used to provoke the bug using:
opt -inline -functionattrs -reassociate reassoc-reduced.ll
The attached file originates from our randomised csmith test suite, but was
reduced to a minimum before inclusion here. I was unable to reduce the command
line to a single pass one.
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